The present invention relates generally to electronic circuits, and more particularly to a high volume expander circuit for restoring the wide dynamic signal range of an audio signal.
Various mediums such as TV, FM and two-track VCR utilize audio signals that have a limited dynamic signal range due to signal format requirements. Such signal formats require that the audio signals at high levels be limited to a predetermined level before being either transmitted or recorded. Due to this, a sound track from a TV broadcast or VCR will not have the same wide dynamic sound as that heard in a movie theater.
In view of the above, devices have been developed to restore the wide dynamic sound of such mediums. One such device is known as a linear volume expander. However, since this device is linear, the audio signals will be expanded at high voltage levels as well as lower levels. This large amount of expansion is undesirable since the sound produced can be unpleasant to the listener. Therefore, it would be desirable to perform volume expansion at high signal levels only.